Density of solutions of protic ionic liquids diethylammonium trifluoromethanesulfonate and triethylammonium trifluoromethanesulfonate and salt tetraethylammonium trifluoromethanesulfonate in N,N-dimethylformamide (DMF) was measured at T = (298.15–348.15) K and atmospheric pressure (p = 0.101 MPa). Apparent molar volumes calculated on the basis of these measurements were approximated by Redlich–Mayer and Mason equations. Standard partial molar volumes (V0) of salts were divided into ionic components () from which, by using the values of intrinsic volume of the ion, volumetric solvation parameters () were calculated. On the basis of the volumetric characteristics obtained, the ion–solvent interaction is discussed. The limiting volumetric properties were compared with the properties of a series of tetraethylammonium ([H(CH2)n]4N+, n = 3–7) cations in DMF.
